Polymer center fire cartridge case for small or medium caliber ammunition and method for manufacturing same

ABSTRACT

An engineered polymer center fire small or medium ammunition cartridge case and methods for manufacturing the same, wherein the engineered polymer material meets the internal &amp; external ballistic standards set by the Sporting Arms and Ammunition Manufacturers Institute and military specifications for center fire rifle small or medium calibers of ammunition cartridges from 0.223 caliber to 30 mm caliber. The cartridge case may allow a projectile to snap into place in the cartridge case mouth after the case is primed and propellant powder is placed into the cartridge case during the cartridge loading process. The rifle cartridge case may be either a single-piece case suitable for use in pistols or a two-piece case suitable for use in rifles, and may be formed by either injection molding or an injection blow molding process. Injection blow molding allows a single piece design. Also disclosed are inventive engineered polymers for use in cartridges.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. Provisional Application No. 62/047,400, filed Sep. 8, 2014, which is hereby incorporated by reference in its entirety.

BACKGROUND

It is well known in the firearms industry that conventional center fire ammunition cartridge cases are constructed from a metallic material (brass or steel) to make it possible to contain the chamber pressures generated by center fire ammunition. It is generally known that metals used to produce ammunition are a resource that is fast being depleted. It is also well known that the military establishment for many years has had the goal of lightening the ammunition weight which burdens the war-fighter. Tangentially lowering the weight of ammunition carried on fighting helicopter missions as well as lowering the weight of transporting ammunition into the theatre of war saves fuel and lowers the logistical problems of resupply in the middle of a critical mission. Lighter weight also means missions can fly farther when necessary.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a polymer center fire small arms ammunition one piece insert according to one embodiment of the invention.

FIG. 2 shows a polymer center fire small arms ammunition cartridge case exterior sleeve suitable for use with the one piece insert of FIG. 1.

FIG. 3 shows the one piece insert of FIG. 1 inserted into the exterior sleeve of FIG. 2 to form a cartridge case according to an embodiment of the invention.

FIG. 4 shows the fully assembled case of FIG. 3 including a primer pocket, a flash hole and a channel between the flash hole and the primer pocket formed therein.

FIG. 5 shows a cartridge case insert bonded into a non-locking polymer sleeve according to another embodiment of the invention.

FIGS. 6 a and 6 b show, respectively, a cartridge case insert and a non-locking polymer sleeve including mating male and female threads according to a third embodiment of the invention.

FIGS. 7 a and 7 b show, respectively, a cartridge case insert including locking rings and a non-locking polymer sleeve including locking channels configured to mate with the locking rings to form a seal according to a fourth embodiment of the invention.

FIG. 8 shows a one piece injection blow molded center fire cartridge case according to a fifth embodiment of the invention.

FIGS. 9A-D illustrate loading of one piece injection blow molded center fire cartridge cases according to alternative embodiments of the invention.

FIG. 10 illustrates loading of primer and a primer cup with a flash hole and channel into a one-piece cartridge case according to yet an embodiment of the invention.

FIG. 11 shows a spring loaded priming tool for inserting primer into a cartridge case.

FIG. 12 a shows the spring loaded priming tool of FIG. 11 a being used to insert a primer assembly into a mouth of the cartridge case of FIG. 8 according to an embodiment of the invention.

FIG. 12 b shows the spring loaded priming tool of FIG. 11 a being used to insert a primer cup assembly into a mouth of the cartridge case of FIG. 8 according to another embodiment of the invention.

FIGS. 13A-E show a single-piece all-polymer cartridge case according to another embodiment of the invention.

DETAILED DESCRIPTION AND BEST MODE OF IMPLEMENTATION

Various polymer center fire small arms ammunition are discussed herein. The polymer center fire small arms ammunition may consist of cartridge cases designed and produced from a polymer, preferably an engineered polymer, which is either injection molded or injection blow molded to form a cartridge cases compliant with either the Sporting Arms & Ammunition Manufacturers Institute (SAAMI) or military standards for small or medium caliber ammunition center fire cartridge case in any center fire caliber. The ammunition may be used with any of a semi-automatic, bolt action or fully automatic rifle firing mechanism to ignite the cartridge primer and the propellant contained in the ammunition cartridge case of this invention. The engineered polymers from which the cartridge cases are produced are capable of containing the interior cartridge case pressures encountered by conventional small arms center fire ammunition. The engineered polymers also do not stress mankind's delicate environment. Furthermore, engineered polymers can provide a finished product design which may be over 50% lighter (case to case comparison) in weight than conventional brass cased ammunition.

A polymer cartridge case-based ammunition may have a generally cylindrical case body configured with a mouth opening, a metered amount of propellant/powder within a volume of space inside of the case cylindrical body, a projectile/bullet loaded into said mouth opening, and an angular groove designed to accept and mate to the extractor of the weapon in which the center fire rifle cartridge of this invention is fired. As used herein, “generally cylindrical” is not limited to cylinders with straight sidewalls and includes cylinders formed with sidewalls having different radii at different points along a central axis. Below the angular extractor groove of the cartridge case is a rim which houses the primer which ignites when struck by the weapon firing pin, and which in turn ignites the powder/propellant that propels the bullet/projectile through the barrel towards the target. As used herein, “rim” refers to an end wall of a generally cylindrical case, not just a portion of an end wall that extends outwardly beyond a sidewall of a generally cylindrical case. As discussed above, the cartridge case is produced from an engineered polymer and manufactured to the design specifications of any chosen SAAMI or military design center fire small or medium caliber ammunition in the SAAMI or military cartridge case library. The cartridge cases may be used in conventionally loaded cartridges containing a small or medium caliber primer or primer system, propellant, and a projectile/bullet which all together function as ammunition suitable for loading and firing in any center fire firearm either of a semi-automatic, bolt action or fully automatic rifle firing mechanism or in a pistol firing mechanism.

Engineered polymers save natural resources and are more recyclable than metals. In some embodiments, the cartridge case is formed from an engineered polymer that contains the pressures experienced in the firing of conventional brass or steel cased small or medium caliber ammunition. The finished engineered polymer cartridge case may equal or exceed the ballistic performance of conventional all-metallic casings. In some embodiments, the engineered polymer provides the cartridge case with high stiffness which is comparable to conventional metallic material toughness and which may offer the ability to produce thinner walls and lighter weight products. Engineered polymers may also provide improved reaction to high heat distortion temperatures, and higher retention of mechanical properties under humid conditions. Additionally, the engineered polymer may have explosive/propellant compatibility and may maximize prohibiting moisture absorption while providing moisture protection given to the complete round of ammunition.

The engineered polymer discussed above may be formed of a nylon resin. Examples of such nylon resins include PA6, NYCOA 8330™ available from Nylon Corporation of America, and RIP 299DX140551™ (natural) from RIP Co. of Winona, Minn. In order to improve the thermal and mechanical properties of cartridge cases made from such nylon resins, various additives may be added. For example, in one embodiment, a nano-composite material comprises a nylon (PA6) base in which nano-clays which are members of the smectite class of layered silicate or platy minerals are dispersed. The nano-clays may include alumino-silicate particles which are uniformly dispersed in a polymer matrix. Another example of a suitable material may be formed from a NYCOA 8330™ base and carbon nanotube (CNT), basalt and/or silica nanoparticle additives. In one embodiment, either CNT, basalt or silica nanoparticle additives are present with weight percentages between 0.25-5, and more preferably 0.5, 1, 1,5 or 2 weight percent. Yet another example includes RTP 299DX140551 base and additives comprising ball-milled ceramic fibers available from Thermal Products Co. of Norcross, Ga. or powdered KEVLAR™ fibers. Beads of such polymers may be molded into the components discussed above using an injection molding or blow molding process. In some embodiments, the material flexibility is sufficient to allow the mouth of the cartridge case to accept a bullet/projectile with an annular groove engaged by a corresponding detent in the mouth, and, in some two piece embodiments described below, is also sufficient to allow an insert to be inserted into a sleeve with a locking tab. (In other two-piece embodiments, the insert is molded or forged first, and then the insert is over molded by the sleeve during an injection molding process to create a unified cartridge case).

Injection blow molding is used in the production of hollow vessels. Just as in injection molding, the polymer material is injected onto a core pin which is next rotated to a station known in the industry as a blow molding station where it is inflated to shape, cooled and then ejected.

The molded coloring of the cartridge case may signify the functional use of each individual round of ammunition. The requisite color system taken from the visible and infra-red color spectrum may determine the difference between ball ammunition, tracer ammunition, training ammunition, sub-sonic ammunition or any other specialty ammunition types. The color may indicate the type, but not the caliber, of the ammunition.

Referring now to the drawings, FIG. 1 shows a polymer center fire small arms ammunition one piece insert 1. The insert 1 may be produced using a forging/pressing of aluminum in one embodiment of the invention. In a second embodiment, the insert 1 can be formed from an engineered polymer material using either injection molding or injection blow molding. The engineered polymer material is especially formulated to withstand the pressure of igniting the primer to initiate firing, and may be the nano-composite material discussed above, but is not so limited. The rim 1 a of the insert is designed to withstand the force of chambering a full up loaded cartridge. The insert 1 and rim 1 a are also designed to effectively extract the fired cartridge case by mechanical means without breaking the rim 1 a of the fired cartridge. The insert also includes an annular groove 1 b spaced apart from the rim 1 a. The purpose of the annular groove will be explained in connection with FIG. 2 below. Finally, the end 1 c of the insert 1 opposite the rim 1 a is beveled for reasons that will be explained below in connection with FIG. 2.

FIG. 2 shows a polymer center fire small arms ammunition cartridge case exterior sleeve 2 designed for use with the insert 1 of FIG. 1. The sleeve 2 includes a locking lip 2 a formed in the cartridge case mouth 2 b. The sleeve 2 also includes a rearward sleeve annular locking tab 2 c, which is configured to mate with the annular groove 1 b of the insert 1. The sleeve 2 further includes a shoulder 2 d which is configured to conform to the beveled end 1 c of the insert 1.

FIG. 3 shows a polymer center fire small arms ammunition cartridge case 300 formed by fitting the sleeve 2 onto the insert the 1. As shown in FIG. 3, the tab 2 c of the sleeve 2 is engaged with the annular groove 1 b of the insert 1, and the exterior surface of the beveled end 1 c of the insert 1 is adjacent the interior surface of the shoulder 2 d of the sleeve 2. A bonding agent may be applied between the two parts, either at only the location where the tab 2 c engages the annular groove 1 b or (also or alternatively) in other places where the sleeve 2 and insert 1 are adjacent. As shown in FIG. 3, when the sleeve 2 is fitted to the insert 1, a substantial portion of the lengths of the sleeve 2 and the insert 1 are overlapping. Preferably, at least a majority of the length of sleeve 2 overlaps at least a majority of the length of the insert 1. More preferably, at least 60% of the lengths of each of the sleeve 2 and the insert 1 overlap each other. In yet other embodiments, the percentage of overlap of each of the sleeve 2 and the insert 1 are 65%, 70%, 75%, 80%, or more.

FIG. 3 also illustrates an annular groove 301 formed in the cartridge case 300 by the combination of a surface of the rim 1 a, a surface of the end of the sleeve 2, and an outer surface of the insert 1 adjacent the rim 1 a. The outer surface of the insert 1 forms part of the groove 301 because the end of the sleeve 2 is spaced apart from the rim 1 a. In other embodiments, the end of the sleeve 2 may contact the rim 1 a, in which case the groove 301 may be formed solely by surfaces of the rim 1 a and sleeve 2. The groove 301 is designed to accept and mate with an extractor (not shown in FIG. 3) of the weapon into which the cartridge is placed.

FIG. 4 shows a fully assembled case including a primer pocket 4 a formed in the rim 1 a, a flash hole 4 c formed in the interior surface of the end wall of the insert 2, and a channel 4 b connecting fluid communication between the flash hole 4 c and the primer pocket 4 a. The flash hole 4 c channel carries the spark that ignites the propellant in the cartridge case. The primer pocket 4 a, the channel 4 b and the flash hole 4 c may be formed in the insert 1 by a mechanical process such as drilling. Alternatively, the primer pocket 4 a, the channel 4 b and the flash hole 4 c may be formed during the molding of the insert 1.

FIG. 5 shows a full-up cartridge case insert 502 bonded into a non-locking polymer sleeve 504. The sleeve 502 has a beveled end to form a cartridge case with an extractor groove 506 similar to the groove 301 discussed above in connection with FIG. 3. In alternative embodiments, the sleeve 502 may have a straight end that abuts the rim 502 a to form a cartridge case without an extractor groove.

FIG. 6 a shows full up cartridge case insert 602 that mates with the polymer sleeve 604 of FIG. 6 b. The end of the sleeve 602 may be beveled to form an extractor groove, or may be straight and abut the rim 602 a of the insert 602 to form a straight walled cartridge case without an extractor groove. The insert 603 includes a male thread 603 protruding from the outer wall 602 b. The male thread 603 is configured to mate with a female thread 605 formed in an interior wall 604 b of the sleeve 604. The threads both form a seal between the insert 602 and the sleeve 604 and mechanically bond the insert 602 and the sleeve 604. In some embodiments, an adhesive is used to bond the threads 603, 603; in other embodiments, no adhesive is used.

FIG. 7 a shows full up cartridge case insert 702 that mates with the polymer sleeve 704 of FIG. 7 b. The end of the sleeve 704 may be beveled to form an extractor groove, or may be straight and abut the rim of the insert 702 to form a straight walled cartridge case without an extractor groove. The insert 702 includes two or more protruding molded locking rings 703 formed on the outside surface of the side wall of the insert, which mate to the annular grooves 705 in the interior surface of the sidewall of the sleeve 704 to form a seal.

FIG. 8 shows a one piece injection blow molded center fire cartridge case 810 which is primed thru the mouth 810 d of the cartridge case 810. The cartridge case 810 includes a rim 810 a into which a primer well 810 c has been formed such that the primer well 810 c is open to the inside of the cartridge case 810 but does not extend to the outer surface 810 b of the rim 810 a. The primer well 810 c may be formed in the cartridge case 810 during the molding process or may be formed afterwards such as by drilling. The primer well 810 c is filled with a primer material 811, which may be placed into the well 810 c through the mouth 810 d using a loading tool that will be discussed in further detail below. When ammunition including a cartridge case 810 are fired from a weapon, a firing pin of the weapon pierces the thin wall of the rim 810 a in the area of the well 810 c to ignite the primer, which ultimately results in the round being fired. Embodiments such as that shown in FIG. 8 that do not have any seams on the outside surface 810 b of the rim 810 a are particularly well-suited for storage and use in wet or damp environments as they prevent moisture from penetrating the cartridge and degrading the primer and propellant inside the cartridge case. It should be understood that the design of the primer well shown in FIG. 8, with a sealed bottom that is not open to the outside such that the primer must be loaded through the mouth of the cartridge, may also be used with two piece casings such as those shown in FIGS. 1-3.

FIGS. 9 a-d are a series of four drawings showing cartridge cases which are all injection blow molded. Each cartridge case is loaded using the priming tool (FIG. 11) to insert the primer 911 into the cartridge case thru the cartridge case mouth. The primer 911 is held into the respective primer well 910 c by a primer well cover 913 through which a flash hole and channel have been formed. The primer well cover 913 is shown in side and top views in FIGS. 9 a-d for the sake of illustration, but only one primer well cover 913 is used in any one cartridge case.

FIG. 9 a shows a primer well cover 913 that is inserted through the mouth the mouth of the cartridge case and set in place over the primer well 910 c and primer 911 by pressure fitting. In an alternative embodiment, the primer well cover 910 c is set in place and made fast using an adhesive.

FIG. 9 b shows a primer well cover 913 with two receptacles 915 formed therein for receiving two pins 914 formed in the base of the cartridge case on either side of the primer seating position.

FIG. 9 c shows a cartridge case with two metal “L” shaped prongs 916 positioned to accept the primer well cover 913 from the priming tool (FIG. 11) and lock it in place.

FIG. 9 d shows a primer well cover 913 with two locator pins 919 on either side of the channel that mate with two locator holes 918 on either side of the primer well 910 c of the cartridge case.

FIG. 10 shows a cartridge case 1010 manufactured by polymer injection molding or injection blow molding into a single piece, and only accessible to the interior by the mouth of the case 1010. FIG. 10 also shows a primer 10 a pictured in the front of the cartridge case mouth with a primer positioning metal cup 10 b in front of the primer 10 a. Both the primer 10 a and the primer positioning metal cup 10 b are loaded into the priming tool (shown in FIG. 11) for loading into the mouth of the case 1010. Where this design greatly differs from existing one piece casings is that in all applications of SAAMI or military standards, the casing is primed from the rear through a molded well in the outside of the base of the case. In this embodiment, priming is conducted internally with an assembly of a plastic or metal cup 10 b with a flash hole which cups and holds the anvil side of the primer 10 a toward the flash hole, and when inserted into the primer well 1010 c through the mouth of the casing butts the primer's firing pin striking surface side against the thinly molded polymer back of the sealed base of the cartridge case 1010. The primer cup assembly is affixed tightly in place with a bonding agent, mechanical hooking method, screw type threading, laser bonding, or combination of these elements of the aforementioned to ensure a solidly affixed primer assembly and rigid surface for the clean strike of a firing pin. Upon the expense of the round, the expended case 1010 can be opened from the rear (if not already opened during firing) to remove the used primer and allow the environmentally friendly polymer round to be 100% recycled, but not reloaded.

FIG. 11 (not to scale) shows a priming tool 1100 for inserting a primer 1111 and a primer well cover 1113. The priming tool 1100 is spring loaded and is inserted through the mouth of a case, and then the plunger 1101 of the tool 1100 is depressed to insert the primer 1111 into the primer well of a cartridge case (not shown in FIG. 11) and to insert the primer well cover 1113 over the primer 1111 and primer well of the cartridge case. It should be understood that multiple primer 1111/well cap 1113 assemblies may be loaded into the tool 1100, and that these assemblies are retained within the cylindrical body of the tool 1100 by a retainer 1103, which is made from a flexible material with a central hole formed therein that allows a well cap 1113 to pass through when the plunger 1101 is depressed. It should be further understood that the plunger 1102 may be activated by or be a part of a machine. In the practice of this invention, there are other mechanical or hand methods that may be implored to achieve insertion of the primer and/or primer cup assemblies.

FIG. 12 a shows loading the primer and primer well cover of FIGS. 9 a-d into a cartridge using the tool 1100 of FIG. 11. Three primer/well cap assemblies are shown in FIG. 12 a for the sake of illustration, but any number of assemblies may be present so that the tool 1100 may be used to load multiple cartridges. FIG. 12 b shows loading the primer and primer cup of FIG. 10 into a cartridge case. Two primer/primer cup assemblies are shown in FIG. 12 b for the sake of illustration, but again any number of assemblies may be present so that the tool 1100 may be used to load multiple cartridges.

FIGS. 13A-E show a single-piece, all polymer cartridge case 1300 suitable for a pistol according to another embodiment. The cartridge case 1300 includes a case body 1302 including a rim 1301 in which a primer pocket 1304 a is formed. The primer pocket 1304 a is in fluid communication with a channel 1304 b that terminates in a flash hole 1304 c formed in the curved interior endwall 1304 d of an interior chamber 1303 of the case body 1300 to provide fluid communication between the primer pocket 1304 a and the interior chamber 1303, which may be filled with a propellant through the mouth 1305 of the case 1300. A locking lip 1306 formed on an interior wall of the case 1300 near the mouth 1305 serves to mate with a corresponding circumferential channel 1316 in a projectile 1310 to secure the projectile in the mouth 1305 of the case 1300. The projectile 1310 includes a case body 1312 with an endwall 1312 a (the wall closest to the flash hole 1304 c of the case 1300 when the projectile 1310 is inserted into the case 1300). The projectile 1310 has an outside diameter D2 that is slightly smaller than the inner diameter D1 of a corresponding portion of the interior chamber 1303 of the casing 1300 to allow the projectile 1310 to be inserted into the casing 1300. The endwall 1312 of the projectile 1310 includes a chamfered edge 1326 that facilitates insertion of the endwall 1312 past the locking lip 1306 of the case 1300 (i.e., the chamfered edge 1326 will exert an outward force on the locking lip 1306 such that the sidewall of the casing 1300 will deform/expand to allow the endwall 1312 of the projectile to be pushed past the locking lip 1306 to a point where the locking lip 1306 mates with the channel 1316 of the projectile 1310).

While various embodiments have been described above, it should be understood that they have been presented by way of example and not limitation. It will be apparent to persons skilled in the relevant art(s) that various changes in form and detail can be made therein without departing from the spirit and scope. In fact, after reading the above description, it will be apparent to one skilled in the relevant art(s) how to implement alternative embodiments.

In addition, it should be understood that any figures which highlight the functionality and advantages are presented for example purposes only. The disclosed methodology and system are each sufficiently flexible and configurable such that they may be utilized in ways other than that shown.

Although the term “at least one” may often be used in the specification, claims and drawings, the terms “a”, “an”, “the”, “said”, etc. also signify “at least one” or “the at least one” in the specification, claims and drawings.

Finally, it is the applicant's intent that only claims that include the express language “means for” or “step for” be interpreted under 35 U.S.C. 112(f). Claims that do not expressly include the phrase “means for” or “step for” are not to be interpreted under 35 U.S.C. 112(f). 

We claim:
 1. A method for manufacturing a center fire small or medium caliber ammunition cartridge case from an engineered polymer material, comprising: providing a nano-composite material resulting from the polymerization of nano-clays which are members of the smectite class of layered silicate or platy minerals which are uniformly dispersed in the polymer matrix; and molding the nano-composite material to form a cartridge case.
 2. The method of claim 1, wherein the cartridge case is a two piece cartridge case.
 3. The method of claim 1, wherein an injection molding process or injection blow molding process is used to form the cartridge case, and the cartridge case is a single piece case.
 4. The method of claim 1, wherein the cartridge case meets existing Sporting Arms & Ammunition Manufacturers Institute (SAAMI) and existing military ammunition design specifications for center fire small or medium caliber ammunition cartridge in all calibers from 0.223 to 30 mm calibers.
 5. A single piece small or medium caliber polymer ammunition cartridge case, comprising: a rim; and a generally cylindrical sidewall integral with the rim; wherein the rim is positioned to seal a first end of the sidewall, a second end of the sidewall is open to form a mouth, and the sidewall and rim form a cavity; and wherein a first surface of the rim in the cavity has a primer well formed therein for accepting primer, the primer well having a depth less than a thickness of the rim such that the primer well does not extend through a second surface of the rim opposite the first surface of the rim, thereby allowing primer to be loaded into the primer well only through the mouth.
 6. A two piece small or medium caliber polymer ammunition cartridge comprising: an insert, the insert including a generally cylindrical sidewall and a rim enclosing one end of the sidewall to form a cavity, an outer surface of the sidewall having an annular groove formed therein spaced apart from the rim; and a generally cylindrical sleeve, the sleeve having an annular locking tab configured to mate with the annular groove of the insert formed on an interior surface; wherein the insert and sleeve are formed from an engineered polymer material with a flexibility sufficient to allow the sleeve to be placed over the insert so that the annular locking tab of the sleeve mates with the annular groove of the insert, and, when the locking tab of the sleeve is mated with the annular groove of the insert, at least 50% of a length of the insert overlaps the sleeve and at least 50% of a length of the sleeve overlaps the insert. 